Inject the input signal. Please keep in mind that in application
code it is almost always wrong to use this wire. It should only be
used to interact with other frameworks/abstractions, and even then
it's probably just a last resort.

When you want to write your own wires, consider using mkPure or the
various variants of it.

Produce once periodically. The production periods are given by the
argument list. When it's [1,2,3] it produces after one second,
then after two more seconds and finally after three more seconds.
When the list is exhausted, it never produces again.